JP2013204978A - Container for food heating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container for food heating capable of beautifully baking a surface of bread and cake because a shape retaining property can be maintained, and because deformation is possible, and excellent in a heat generating property and a heat retaining property.SOLUTION: A container 1 for food heating includes a heat generating layer 2 containing a ferrite material 2a in a silicone resin 2b, and a silicone resin layer 3 covering a surface of the heat generating layer 2, the ferrite material 2a being granular. A shape retaining property of a fluid food material is easily maintained since the ferrite material 2a is granular, and the container 1 for food heating follows and easily sticks to the surface of a food material 4 since the container 1 for food heating is deformable, thereby the surface of the food material 4 can be beautifully baked.

Description

  The present invention relates to a food heating container.

  There is a great demand for heating foods using microwave-heated containers such as microwave ovens, and there is a known technology that uses a ferrite material in the container to generate heat, and when this ferrite material reaches the Curie temperature, it stops heating by microwaves. ing. For example, as disclosed in Patent Document 1, in order to thaw foods such as sushi, a frozen food having a heat generating layer that absorbs microwaves and generates heat, and the surface of the heat generating layer is coated with a resin. Tray and frozen food packages are known.

JP 2008-131923 A

  However, in the frozen food tray and frozen food package disclosed in Patent Document 1, food that can be thawed but needs to be baked, such as bread and cake, etc., especially food that easily shrinks when heated. When cooking the food, the container cannot be deformed following the shrinkage of the food, so the surface of the container is separated from the food and the surface of the food cannot be baked cleanly.

  Further, if the ratio of the ferrite material in the heat generation layer becomes too large, the energy of the microwave is dispersed and the temperature is not easily raised, so that the food material may not be baked.

  Further, if the composition of the ferrite material in the heat generation layer is too large, the heat conduction by the ferrite material becomes too high and the heat is easily dissipated, so that the heat retaining property of the container (foodstuff) may be lacking.

  The food heating container of the present invention is a food heating container having a heat generation layer containing a ferrite material in a silicone resin and a silicone resin layer covering the surface of the heat generation layer, and the ferrite material is granular. It is characterized by that.

  According to the food heating container of the present invention, the food heating container has a heat generation layer containing a ferrite material in a silicone resin and a silicone resin layer covering the surface of the heat generation layer, and the ferrite material is granular. As a result, it becomes easy to maintain the shape retention of fluid food materials, and since it is a deformable food heating container, for example, a paste-like material that shrinks when heated, such as bread or cake Even if it is a foodstuff, it becomes easy to bake the surface of a foodstuff cleanly because the container for food heating follows and adheres easily to the surface of a foodstuff.

  In particular, when the ferrite material becomes granular and the total surface area of the entire ferrite material in the heat generation layer increases, the area that receives the microwave increases, and thus heat generation easily occurs.

  In addition, it becomes easy to provide a container for heating food that is excellent in heat retaining property of the container (foodstuff) by using the silicone resin as a heat insulating material and insulating each granular ferrite material in the heat generating layer. Become.

It is sectional drawing of 1st embodiment of the container for food heating of this invention. It is sectional drawing of 2nd embodiment of the container for food heating of this invention. It is a graph which shows an example of the temperature dependence of the magnetism (holding power) of the exothermic layer in the container for food heating of the present invention. It is a graph which shows an example of the microwave application time dependence of the temperature of the heat generating layer in the food heating container of the present invention.

<Food heating container>
Hereinafter, an embodiment of a food heating container of the present invention will be described with reference to the drawings.

  An embodiment of the food heating container according to the present invention is a food heating container having a heat generation layer containing a ferrite material in a silicone resin and a silicone resin layer covering the surface of the heat generation layer, the ferrite The material is granular.

  For example, as in the example shown in FIG. 1, a food heating container 1 includes a heat generating layer 2 in which granular ferrite material 2a is dispersed in a silicone resin 2b, and silicone that covers the front and back (inside and outside) of the heat generating layer 2. And a resin layer 3.

  Here, the shape of the food heating container 1 may be any shape according to the application to the food material 4 such as a bowl shape or a tray shape.

  The ferrite material 2a is a magnetic body that has an appropriate coercive force (for example, the coercive force of the ferrite material 2a at 25 ° C. is 60 to 20 Oersted) and a Curie temperature, and can be heated by microwaves.

  And even if the foodstuff 4 shrink | contracts by having the heat generating layer 2 which consists of the silicone resin 2b containing this ferrite material 2a, and the silicone resin layer 3 which coat | covers this heat generating layer 2, the silicone resin 2b and the silicone resin layer 3 follows the contraction of the food material 4, so that it can be kept in close contact with the food material 4 and heated, and the surface of bread, cake, etc. can be easily baked uniformly.

  Moreover, since the granular ferrite material 2a in the silicone resin 2b serves as a wedge, the strength of the heat generating layer 2 as a whole can be reinforced, so that the shape retention of the food heating container 1 can be maintained, and the food material 4 is a paste. Even if it is in a shape, it becomes easy to keep a certain shape.

  In addition, since the ferrite material 2a is appropriately dispersed in the silicone resin 2b, it is easy to provide the food heating container 1 suitable for heat generation and heat retention.

  Furthermore, as one embodiment of the food heating container of the present invention, the ferrite material has a Curie temperature of 180 ° C. to 220 ° C., and the mass ratio of the ferrite material to the silicone resin in the heat generation layer is 1: 1 to 1: 3 is preferred.

Thereby, the relationship between the heat generation property and the heat dissipation property of the heat generating layer 2 can be set so as to be optimum for cooking of the food material 4, and the food material 4 can be easily baked and the food material 4 is hardly cooled. Can do.

  Further, by appropriately dispersing the ferrite material 2a, the food heating container 1 can be easily deformed according to the shrinkage of the food material 4, and the decrease in shape retention can be reduced.

  Here, the thickness of the heat generating layer 2 is preferably 1 to 3 mm from the viewpoints of heat generation, heat retention, deformation and shape retention of the food heating container 1.

  Furthermore, as one embodiment of the food heating container of the present invention, the ferrite material preferably includes a plurality of types of ferrite materials having different magnetic temperature dependencies.

  Thereby, for example, when applying a microwave, a ferrite material 2a having a high temperature rising rate in a low temperature region and a ferrite material 2a excellent in temperature stability in a high temperature region are combined to obtain a desired temperature. It can be easily set so as to have dependency magnetism (temperature history).

  For example, as shown in FIG. 3, since the coercive force of the ferrite material 2a decreases as the temperature increases, the temperature does not increase any more when the coercive force becomes zero (when the Curie temperature is reached).

  Therefore, as shown in FIG. 4, the temperature increases as the microwave application time is lengthened, but when reaching the Curie temperature, the temperature tends to saturate.

  In order to adjust such a temperature history so as to be optimal for cooking of the food material 4, a plurality of types of ferrite materials 2a may be mixed and dispersed in the silicone resin 2b.

  For example, by mixing each ferrite material having a temperature history of a, b, c in FIGS. 3 and 4 at an arbitrary ratio, it becomes easy to freely obtain a ferrite material 2a having a desired temperature history.

  Such magnetic characteristics can be measured using a sample vibration magnetometer (VSM) or a Kerr effect measuring device.

  Here, the plurality of types of ferrite materials may not be collected as one ferrite material 2a, but may exist independently as individual ferrite materials 2a.

  Furthermore, as one embodiment of the food heating container of the present invention, the ferrite material preferably contains at least magnesium (Mg).

  This makes it possible to improve the rate of temperature rise in the low temperature range by including a ferrite material having excellent heat generation in the low temperature range, and in the high temperature range by appropriately combining ferrite materials having different Curie temperatures. It becomes easy to obtain the heat generating layer 2 having excellent temperature stability.

  Furthermore, as one embodiment of the food heating container of the present invention, it is preferable that the heat generating layer further includes a granular alumina material.

  Thereby, even if the foodstuff 4 does not touch the food heating container 1 directly, it becomes easy to heat the inside of the foodstuff 4 by far infrared rays.

For example, as shown in FIG. 2, the alumina material 2c may be dispersed in the heat generating layer 2 similarly to the ferrite material 2a.

  At this time, it is preferable that the alumina material 2c is arranged to be biased toward the food material 4 in terms of easily heating the food material 4 efficiently.

  Furthermore, as one embodiment of the food heating container of the present invention, the average particle diameter of the ferrite material is preferably 0.8 μm to 3 μm.

  Accordingly, the ferrite material 2a can efficiently absorb the microwaves and generate heat, so that the temperature raising rate can be easily improved.

  Moreover, the ferrite material 2a becomes a wedge effect, and it becomes a suitable particle diameter to make it easy to maintain the shape retention by the silicone resin 2b.

  Moreover, since the area | region of the silicone resin 2b which exists between the ferrite materials 2a can be ensured as a heat insulation layer, it becomes easy to improve heat retention.

  The particle size distribution of the ferrite material 2a can be measured by laser diffraction or the like in a 1 mm square range, and the average particle size can be calculated based on this result.

  Furthermore, as one embodiment of the food heating container of the present invention, the thickness of the silicone resin layer 2b is 0.6 to 1.4 mm, particularly in the heating temperature range of 180 ° C. to 220 ° C. The transfer rate of heat from 2 to the food 4 is the most appropriate thickness.

  Moreover, since the ferrite material 2a having the above average particle diameter protrudes and has a thickness that is difficult to be exposed, and the ferrite material 2a can be reduced from being seen through the surface of the food heating container 1, the decorativeness can be improved. .

  In addition, it is preferable that the thickness of the heat generating layer 2 is 1 to 3 mm from the viewpoint of heat retention, deformability, and shape retention.

<Method for producing food heating container>
Hereinafter, the manufacturing method of the container for food heating of this invention is demonstrated.

  The ferrite material 2a is a ceramic mainly composed of iron oxide, and indicates a material exhibiting soft magnetism or hard magnetism as a ferromagnetic material, and is used from spinel ferrite, hexagonal ferrite, garnet ferrite or the like depending on the crystal structure.

Spinel ferrite has a spinel crystal structure, the composition formula is AFe ₂ O ₄ (A is Mn, Co, Ni, Cu, Zn, Mg, etc.), high magnetic permeability, and high electrical resistance. Here, the ratio of spinel and α ferrite may be set appropriately.

Hexagonal ferrite has a magnetoplumbite-type hexagonal crystal structure, a composition formula is AFe ₁₂ O ₁₉ (A is Ba, Sr, Pb, etc.), and has a larger magnetic anisotropy than spinel ferrite. Therefore, it shows a large coercive force.

Further, garnet ferrite has a garnet crystal structure, the composition formula is RFe ₅ O ₁₂ (R is a rare earth element), and the magnetic loss in the high frequency region is small.

These ferrite materials can also be applied in combination at appropriate ratios as the ferrite material 2a of the food heating container 1 of the present invention. Such a ferrite material 2a is, for example, as follows: can get.

For example, a (MgZn) Fe ₂ O ₄ ferrite sintered body can be obtained by firing (Mg _a Zn _b ) _c Fe ₂ O ₄ ferrite powder.

Then, it can be obtained by grinding up by the _{(Mg a} Zn _b) dispersing the c _Fe 2 _{O 4} ferrite sintered body, the ferrite material 2a having an average particle diameter 0.1μm~10μm about granular.

Silicone resin 2b refers to a polymer obtained by hydrolyzing various silanes including dichlorodimethylsilane and dehydrating condensation of the generated silanol (R ₂ Si—OH), and has a siloxane bond as the main skeleton. (Si—O—Si) is a material suitable for the food heating container 1 in that the bond of the main skeleton is strong, the heat resistance, which is the most basic feature, is exhibited, and it can withstand high temperatures exceeding 200 ° C. .

  Furthermore, although it is gradually denatured (for example, polymerized by dehydration polymerization with oxygen) or decomposed into silica and carbon dioxide (for example, low molecular weight by the formation of cyclic siloxane) at high temperatures, the rate is slow and stable. In addition, it is a material suitable for the food heating container 1 from the viewpoint of low physiological activity.

  As described above, the silicone resin 2b is applied to the material of the food heating container 1 of the present invention, and such a silicone resin 2b is obtained, for example, as follows.

  First, metal silicon and methyl chloride are heated to around 300 ° C. in the presence of a copper catalyst to produce silanes mainly composed of dimethyldichlorosilane.

  Subsequently, in a hydrolysis and dehydration condensation process, it is obtained by removing a by-product through a rectification process.

  The kneading of the ferrite material 2a and the silicone resin 2b is preferably carried out by adding the ferrite material 2a little by little at the stage of generating the silicone resin 2b, for example, the stage of heating the metal silicon and methyl chloride. .

  By flowing this in a mold, for example, it can be formed into a bowl shape having a thickness of 0.1 to 10 mm to form the heat generating layer 2.

  The food heating container 1 of the present invention can be obtained by integrating the sheet-like silicone resin layer 4 on the surface of the heat generating layer 2 by attaching it separately by thermocompression bonding or adhesion.

(Sample preparation)
Prepared _{(Mg a Zn b) c Fe} 2 O 4 ferrite powders of each composition for sintering, having respective Curie temperature _{(170 ℃ ~230 ℃) (Mg} a Zn b) c Fe 2 O 4 ferrite A sintered body was obtained.

Next, this (Mg _a Zn _b ) _c Fe ₂ O ₄ ferrite sintered body was pulverized by a ball mill until it became a granular ferrite material 2a having each average particle diameter (0.7 μm to 4 μm).

  This ferrite material 2a is kneaded with the silicone resin 2b in the middle of production at each composition ratio (ferrite material: silicone resin = 1: 0.5 to 4), then poured into a mold, and formed into a 2 mm thick bowl shape. The heating layer 2 was designated.

  And the sheet-like silicone resin layer 4 of each thickness (0.5 mm-1.5 mm) was affixed on the surface of this heat-generating layer 2 by thermocompression bonding, and it was set as the food heating container 1. In this manner, Samples 2 to 18 which are examples of the present invention were produced.

  As a comparative example, the heat generation layer 2 is not a granular ferrite material 2a but a sheet-like ferrite and is coated with a silicone resin layer 3, and this is used as a sample 1.

(Evaluation method)
As the foodstuff 4 used in the present Example, the paste for sponge cake was used, and what put this in each food heating container 1 of the above-mentioned samples 1-18 was prepared.

  This is irradiated with microwaves under conditions of 2.45 GHz, 500 W, 10 seconds to 90 seconds in a microwave oven, and the shape of the food 4 after cooking is not broken, or the surface of the food 4 for the condition of baking It was evaluated by a visual sensory test by 10 arbitrary housewives whether or not it was evenly burned and heated to the inside.

  As for the shape of the food material 4, the case where cracks were not confirmed in the food material 4 was marked with ◎, the case where cracks were present but the shape was not broken was marked with ○, and the case where the shape was broken was marked with ×.

  Regarding the baking condition of the food material 4, the case where the surface of the food material 4 was not burnt and was heated to the inside of the food material 4 was marked ◎, and the case where the food material 4 was burnt or not heated to the inside was marked as x.

  As supplementary evaluation data, by measuring the surface temperature of the side surface of the food heating container 1 as needed using a radiation thermometer, the speed of the temperature rising rate at the initial stage of microwave irradiation, and during microwave irradiation The stability of the saturation temperature and the heat retention after microwave irradiation were evaluated.

  Regarding the speed of the heating rate in the initial stage of microwave irradiation, the heating rate in the initial stage is 5 ° C./second or more and 10 ° C./second, ◎ 3 ° C./second or more and less than 5 ° C./second or 10 ° C. The case of ≧ 3 ° C./second or the case of 13 ° C./second or more was evaluated as “x”. Here, if the rate of temperature increase is too fast, it will burn, and if it is too slow, the cooking time will be excessive.

  Regarding the stability of the saturation temperature during microwave irradiation, ◎ if the temperature change after temperature saturation is less than ± 2 ° C, ○ if it is more than ± 2 ° C and less than ± 5 ° C, and if it is more than ± 5 ° C. X.

  Regarding the heat retention after microwave irradiation, ◎ if the temperature drop rate after irradiation is 0 ° C / second or more and less than 0.1 ° C / second, ○ if 0.1 ° C / second or more and less than 1 ° C / second, The case of 1 ° C./second or more was evaluated as x.

(Results and Discussion)
The evaluation results are shown in Table 1.

  It turned out that about the samples 2-6 which are the Examples of this invention, the Curie temperature of the ferrite material 2a has preferable 180 to 220 degreeC.

  In this range, the magnetization of the ferrite material 2a disappears when the temperature rises to just a good temperature when baking bread or cake, so that the ferrite material 2a is not heated at a temperature higher than necessary. It is considered that the shape and baking conditions were good.

  Regarding samples 7 to 10 which are examples of the present invention, it was found that the mass ratio of the ferrite material 2a and the silicone resin 2b in the heat generating layer 2 is preferably 1: 1 to 1: 3.

  If it is in this range, the burning due to the rate of temperature rise being too fast and cracks due to deterioration of the heat retaining properties due to the mutual contact between the ferrite materials 2a are reduced. It is considered that the baking condition was good.

  It turned out that about the samples 11-14 which are the Examples of this invention, the average particle diameter of the ferrite material 2a has preferable 0.8 micrometer-3 micrometers.

  If it is this range, while being able to absorb a microwave efficiently, the burning by the rate of temperature rise being too fast, and the crack by the heat retention worsening because the ferrite materials 2a contact each other are reduced, especially It is considered that the food 4 of the samples 12 and 13 is well baked.

  It turned out that about the samples 15-18 which are the Examples of this invention, the thickness of the silicone resin layer 2b has preferable 0.6-1.4 mm.

  Within this range, the heat transfer rate from the ferrite material 2a to the food material 4 is just improved, so it is considered that the food material 4 is well baked, especially for the samples 16 and 17.

  Here, the thickness 0.6 to 1.4 mm of the silicone resin layer 2b has the highest heat transfer rate from the heating layer 2 to the food 4 at a temperature 180 ° C to 220 ° C most suitable for cooking of bread and cake. It may be considered that the thickness is appropriate and hardly depends on the thickness of the heat generating layer 2 (practically in a range of about 1 mm to 3 mm).

  And among the Example of this invention, the thing by the container 1 for food heating of the sample 4 is the most excellent and optimal conditions at the point of the shape of the foodstuff 4, a baking condition, a temperature increase rate, a saturation temperature, and heat retention. I understood it.

  In contrast to these examples, for sample 1 which is a comparative example, since heat generation layer 2 is a sheet-like ferrite, heat conduction is increased, and thus the heat transfer rate from heat generation layer 2 to food 4 is high. It was found that the surface of the food 4 was burnt because it was too fast.

  Similarly, since the heat generating layer 2 is a sheet-like ferrite, the heat conduction is increased, so that the heat release becomes too fast and the temperature during the microwave irradiation tends to fluctuate, and after the microwave irradiation, It has been found that cracks are likely to enter the food material 4 because the rate of decrease in temperature at this time has increased.

1: Food heating container 2: Heat generation layer 2a: Ferrite material 2b: Silicone resin 2c: Alumina material 3: Silicone resin layer 4: Food material

Claims (7)

A heating layer containing a ferrite material in a silicone resin;
A food heating container having a silicone resin layer covering the surface of the heat generating layer,
A container for heating food, wherein the ferrite material is granular.   The food heating according to claim 1, wherein the ferrite material has a Curie temperature of 180 ° C. to 220 ° C., and a mass ratio of the ferrite material to the silicone resin in the heat generation layer is 1: 1 to 1: 3. Container.   The container for heating food according to claim 1 or 2, wherein the ferrite material includes a plurality of types of ferrite materials having different magnetic temperature dependencies.   The food heating container according to claim 1, wherein the ferrite material contains at least Mg.   The said heating layer is a container for food heating in any one of Claims 1-4 which further contains a granular alumina material.   The food heating container according to claim 1, wherein the ferrite material has an average particle size of 0.8 μm to 3 μm.   The food heating container according to any one of claims 1 to 6, wherein the silicone resin layer has a thickness of 0.6 to 1.4 mm.

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